Those things crossed the mind of Carl TenPas some five or six years ago as he picked up the rock, but they didn’t linger.

Instead, TenPas set it aside as an interesting specimen from a hike, but gave it little more thought.

That was until last month, when he read a story in The Daily Sentinel about a rounded stone that had been used as .75 caliber ammunition. Possibly, he thought, his find might have served a similar function.

“I’d never seen (a rock) that spherical,” TenPas said

However spherical, the rock was unlikely to have been used for ammunition because of its slightly irregular shape, said David Bailey, curator of history for the Museum of Western Colorado in Grand Junction.

The rock, a bit larger than a baseball and a bit smaller than a softball, might have been shaped and used for a variety of purposes, Bailey said.

Intrigued, Bailey called in John Foster, curator of paleontology, to take a look at TenPas’ find. Its volcanic nature suggests an origin in the basalt cap of Grand Mesa, and its shape could well have been the result of grinding and polishing in a river, Foster said.

The problem in fixing a theory to the find is that no one knows where the rock was.

TenPas remembers only the slightest of detail about finding it, enough that he can rule out any chance he found it along a river or stream. The most likely scenario is that TenPas spotted the rock as he hiked in the Kodels Canyon area, he said.

Surmising the rock’s back story is guesswork at best, Bailey and Foster said.

Such finds should be reported to the Bureau of Land Management or other appropriate agency so they can be classified and studied, Bailey said.

Without the context of its surroundings and the kinds of conclusions that might be drawn from them, Bailey said, TenPas’ find is most likely to remain what it was when he found it: a mystery.